<?php
/**
 * first filter
 * User: Administrator
 * Date: 2017/12/6
 * Time: 14:25
 */

$int = "111.1";

if(!filter_var($int, FILTER_VALIDATE_INT))
{
    echo("不是一个合法的整数");
}
else
{
    echo("是个合法的整数");
}
?>